The last step in the change is the action of thrombin upon fibrinogen to form fibrin, and the clot is complete.
First, it is found that thrombin becomes converted very quickly into an inactive modification.
The coagulating enzymes, such as thrombin or thrombase (the fibrin ferment) and rennin, which causes the clotting of milk.
thrombin, on the other hand, does not exist in living blood, but only makes its appearance there after blood is shed.
It is not yet certain what is the nature of the final reaction between fibrinogen and thrombin.
thrombin throm·bin (thrŏm'bĭn)
An enzyme in blood formed from prothrombin that facilitates blood clotting by reacting with fibrinogen to form fibrin. Also called thrombase.